I have a trane XE 90 that is mounted in the attic. The unit will run when the heat is selected at the thermostat but the unit does not light and just blows cold air.
Help!

Well first you have to get in front of the unit have it call for heat so you can see
whats going on. See if you have a lite blinking that gives you a code that you can look up in your book. This is what happens when is calls for heat.
First inducer starts.
prep urge for 30 seconds.
then glow bar start to heat up for 15 to 30 seconds.
then main gas open and burner fires up.
If you don't get fire up , the blower will still come on.
There are a lot of things that can stop a unit from firing.
Do you have a way of testing 24 and 110 volt power? Paul

Been here a long time Paul. Long enough to know that a tech will be called in to fix the problem. People can't buy the parts over the counter unless they have the contractor license. In the last month, I've had to replace 4 glow bars, 5 control boards, 1 inducer motor and 3 flame sensors. All on Trane units. It just seems like they have more problems than any other brand I have to service.

Been here a long time Paul. Long enough to know that a tech will be called in to fix the problem. People can't buy the parts over the counter unless they have the contractor license. In the last month, I've had to replace 4 glow bars, 5 control boards, 1 inducer motor and 3 flame sensors. All on Trane units. It just seems like they have more problems than any other brand I have to service.

Parts are available on the internet. You just have to search. Also 110V upgrade nitride ignitors are now available at some big box stores. Seems to me that possibly Tranes are the majority of your work and that you WOULD see more problems with trane than other equipment. All manufacturers furnaces have failures, there is not one that has fewer failures than another. Most of what makes the difference is how well it was installed.

BTW, flame sensors almost never need replaced unless the porcelain cracks. They are just a metal rod and can be cleaned of invisible oxides and deposits very easily. It is doubtful that you needed to replace all those flame sensors IMO.

Parts are available on the internet. You just have to search. Also 110V upgrade nitride ignitors are now available at some big box stores. Seems to me that possibly Tranes are the majority of your work and that you WOULD see more problems with trane than other equipment. All manufacturers furnaces have failures, there is not one that has fewer failures than another. Most of what makes the difference is how well it was installed.

BTW, flame sensors almost never need replaced unless the porcelain cracks. They are just a metal rod and can be cleaned of invisible oxides and deposits very easily. It is doubtful that you needed to replace all those flame sensors IMO.

Very well said hvactechfw. I know in my area is a person call me and he wants to, and has the know how to fix his own furnace i will sell him parts at the right price and we also have a wholesaler in my area that will sell to them.
I am not sure if this ever changed or not. But a few years back it was against the law for a wholesaler to refuse to sell to a home owner, they did have the right to raise the price. There is enough people around for me to make money from, and my service man stays on the go and makes good money. So i don't mind helping somebody out that needs its or wants the
satisfaction of putting in there own heating system or fixing there own furnace. I will sell them the material at a reduced cost and do the engineering
for them so there system works right when they are done. Paul